U.S. Pat. Nos. 4,498,803, 4,500,225 and 4,624,601 disclose a transferable lane barrier system for roadways adapted to be lifted by a transfer vehicle and moved to a selected position on a roadway or the like. Lane barriers of this type find particular application at roadway construction sites and on roadways and bridges wherein the groupings of incoming and outgoing lanes of traffic must be varied, particularly during commute hours.
Prior to the advent of the lane barrier system disclosed in the above patents, lane barrier systems used at construction sites normally constituted individual, steel-reinforced concrete modules. The modules, arranged in tandem relationship, were and still are used to separate lanes of traffic from a construction area for safety purposes. The modules require the use of cranes and the like to selectively place and remove the modules. This procedure is obviously time consuming, labor intensive and expensive to use.
In respect to commuter lanes and bridges that exhibit a high propensity for head-on collisions, the lane barrier system disclosed in the above patents has provided a solution to the long-standing need for providing an effective and transferable crash barrier separating incoming and outgoing lanes of traffic. Prior to the advent of this lane barrier system, lanes of traffic were solely divided by flimsy delineators or posts that provided no protection against head-on collisions.
For example, the Golden Gate Bridge in San Francisco and its connector, Doyle Drive, are even now using upstanding plastic posts having pins secured on their lower ends to facilitate transfer of the posts from lane to lane to accommodate changes in commute hour traffic. This system has proved inadequate for protecting against head-on collisions, as evidenced by four fatalities and numerous injuries that have occurred during the first four months of 1988. Further, minimal protection is provided for the workmen required to change the posts from lane-to-lane from a truck.
The lane barrier system disclosed in the above patents has worked quite well when placed in operation to prevent a passenger car from leaving its lane when it impacts the barrier system. The present invention provides an improved lane barrier system in respect to its ability to prevent a passenger car or the like from riding or catapulting over the modules thereof. In particular, applicant has determined that consideration should be given to the profile design of the module's sidewalls and reinforcement, relative to the configuration of the bumper systems of passenger vehicles and light duty trucks.
Conventional bumper systems are normally the first portion of a vehicle to impact the barrier system, as evidenced by extensive experimental tests conducted thereon. The Society of Automotive Engineers, Inc. has issued SAE Standard J689 which recommends standards for the bumper systems for passenger cars, station wagons and light duty trucks. In particular, under full rated load, the minimum approach, departure and ramp brakeover angles of such a vehicle are recommended as 16.degree., 10.degree. and 10.degree., respectively. Further, SAE recommended practice J980a sets forth a bumper evaluation test procedure for passenger vehicle bumper systems.
In addition to addressing the above-described anti-crash problem, another aspect of this invention solves the long standing problem of providing a lane barrier system that will elongate or contract to accommodate positioning of the system at varied radii on a curved roadway. The system disclosed in the above patents, particularly useful for straight-line roadway applications, utilizes a hinge connection between each adjacent pairs of modules having aligned circular holes, formed in overlying hinge plates, adapted to receive a hinge pin therethrough. Even when the holes are lined with a thin (e.g., 1/8" wall thickness) elastomeric bushing, the modules are incapable of elongating as a unit when the system is moved radially on a curved roadway.
For example, it has been determined that when the system is moved from a 1200 ft. radius to a 1212 ft. radius, the composite length of the lane barrier system must increase by approximately 0.25 in. for each three feet in length of the barrier system to effectively accommodate this new position on the same, curved roadway. Conversely, repositioning of the barrier system radially inwardly to a new position on the curved roadway, having a radius of curvature of 1188 ft., will require a corresponding contraction of the composite length of the lane barrier system. In the above example, it should be understood that the ends of the barrier system are located at the same relative radial position on the curved roadway to thus require the aforementioned composite elongation or retraction of the system.
One solution to the latter problem of compensating for curvatures of varied radii on a curved roadway is to substitute elongated slots for the pin-receiving circular holes, normally formed in the hinge plates. The slots allow the lane barrier system to assume various radii, as described in the above example. However, it is further desirable to return the spacing between each adjacent pair of modules to a nominal one when the barrier system is loaded on a transfer vehicle and returned to its normal position on a roadway, e.g., the above-mentioned radius of 1200 ft.
Repeated transfer of the modules having slotted hinge pins will tend to "stack-up" the modules towards one of the ends of the lane barrier system which interferes with effective transfer and placing of the modules in their correct positions. In particular, it is desirable to maintain the pivot pin between each adjacent pair of modules at a centered position therebetween (and reestablish the nominal spacing) when the barrier system is returned to its nominal position on a roadway. This feature, when achieved, will facilitate the efficient transfer of the system by the type of transfer apparatus described in the above patents.